Virginia Triangle – feeding Adelaide’s garden
Australia’s largest water recycling scheme employs a new rubber ring joint system now available in Europe.
The significance and scale of South Australia’s Virginia Irrigation Scheme
is evident in its project history. Taking 20 years to initiate and 2.5 years
in planning negotiations, the scheme has now been completed, following an 18
month construction programme. The result is a technologically advanced water
recycling system that is the largest, not just in Australia, but in the whole
of the southern hemisphere.
Known as the Virginia Triangle, the focus of the scheme is a key agricultural
area on Adelaide’s Northern Plain, which provides the food bowl for Adelaide’s
fresh vegetable supply. This vast market garden has grown to meet demand over
100 years of operation, placing an increasing strain on the area’s freshwater
resources. The crop farming community had suffered from a receding and increasingly
saline water table, until the new irrigation system came on stream.
Some 230 individual properties are now served with a continuous and secure
supply of ‘A’ grade (Californian Standard) water from the new Bolivar
treatment plant near the Adelaide conurbation. A network of ABS plastic pipes,
totalling 186 km, currently delivers the water at a rate of 110 Ml/day, which
makes a large reduction to the treated wastewater outflow into coastal waters,
while providing crop irrigation.
The pipe network is record breaking in its own right, incorporating the world’s
largest ABS pipe diame ters, up to 826 mm on the two trunk mains. Manufactured
and supplied by Tyco Water Plastic Pipeline Systems (Eurapipe), the pipe system
used two joining methods.
Together with conventional solvent cement welding, used over much of the network,
Eurapipe elsewhere employed their more recently introduced rubber ring joint
system. Using these joining methods, trained teams of contractors achieved pipe
laying rates of 300 metres per day on the large diameter sections. The ABS pipe
system is widely used in the Australian water industry and is now available
in Europe from the UK distributor, EPCO.
The rapid installation and success of the Virginia Irrigation Scheme overall
mean that it is soon likely to be replicated. Tyco, with its joint venture partners
Multiplex and Gutteridge, Haskins and Davey, are working on a similar proposal
for Melbourne Water’s Eastern Treatment Plant. Large diameter sections
were laid at a rate of 300 metres per day.